


Scrappy Kid

by SailorChibi



Category: Marvel Cinematic Universe, The Avengers (Marvel Movies)
Genre: Age Play, Angst with a Happy Ending, Baby!Tony, Bathing, Bucky Barnes Needs a Hug, Carrying, Confused Steve Rogers, Confusing relationships, Cuddling, Daddy!Steve, Diapers, Domestic Avengers, Emotional Hurt/Comfort, Feeding, Gen, Happy Ending, Hugging, Hurt Tony Stark, Hurt/Comfort, Infantilism, Jealous Steve, Little!Tony, No Romance, Pacifiers, Platonic Cuddling, Protective Bucky Barnes, Team as Family, Tony Stark Needs a Hug, actual communication, angst with fluff, bottles, bucky barnes is a mother hen, daddy!Bucky, falling into age play naturally, in a marvel fic, non sexual age play, non sexual infantilism, slow burn age play, tony stark is a little shit, what is the world coming to
Language: English
Status: Completed
Published: 2017-01-21
Updated: 2017-02-25
Packaged: 2018-09-18 21:31:42
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 11,572
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9403697
Author URL: https://archiveofourown.org/users/SailorChibi/pseuds/SailorChibi
Summary: It all started with what was meant to be a joking comment. Now it's the one where Tony and Bucky naturally fall into an age play relationship, and somehow Steve gets mixed up in it too.





	1. Chapter 1

**Author's Note:**

> This story is a commission for an anon, who wanted motherhen!Bucky and secretly enjoying it!Tony to fall into a (non sexual) age play relationship thanks to what was supposed to be a joke from Tony, followed by a slightly jealous Steve. I fell in love with the idea and really hope I can deliver.

It takes time for Bucky to get used to being in Avengers tower, and to being with Steve again. Actually, if he were being honest, he would have to admit that the latter is a hell of a lot harder on the head than the former. Because it doesn't take long for Bucky to realize that Steve doesn't need him anymore. And he doesn't mean in that the dramatic, 'oh woe is me' way that modern day soap operas are so fond of. It's just that Steve is Captain America, the pinnacle of human health and perfection. He's not sick anymore, he barely needs to sleep, has all the food he could ever want available to him, and is more than capable of handling any fights that he gets into. 

So it's weird for a little while, because part of Bucky's head still remembers that scrappy little shit who _did_ need him and that turns out to be what Bucky misses the most. They actually come close to clashing a couple of times; he and Steve have a couple of pretty loud arguments before Sam rather forcefully points out how damned stupid the two of them are being and forces them to sit down and talk like the grown up children they are (Sam's words, not Bucky's). The end result of that conversation is that Steve promises to be more understanding and Bucky promises to back off.

And he follows through on that promise - with Steve anyway.

"Tony Stark, what is the matter with you?"

"Nothing. There is absolutely nothing wrong with me. I'm completely healthy."

"That's not what Bruce tells me," Bucky says, hands on his hips.

"Bruce is a filthy traitor," Tony calls out. He's mostly hidden from Bucky's view, flat on his back underneath an old car that he recently purchased at an auction. Bucky can hear the clink of tools against the car's undercarriage. Part of him is tempted to just let Tony keep working, because he knows how vested Tony is in restoring this car, but a much bigger part is more concerned with the report of the attempted kidnapping that Bruce passed onto him when Bucky returned to the tower. Next time Natasha suggests that he join her on a SHIELD mission, Bucky is going to tell her to shove it.

He puts a foot on the edge of the creeper. "You can come out on your own or I can make you come out," he says firmly. There’s a reason that Bruce came to him about this: Tony doesn’t listen to anyone else on the team. He stiffens up like an offended cat when they try, especially Steve. But Bucky, for whatever reason, has somehow weaseled his way in past those defenses. As a result, he is now officially the Tony-wrangler of the team. It’s a position he might love, even if – were it not for the serum – Tony would be turning his hair grey with stress.

Tony heaves a put-upon sigh and obligingly scoots the creeper out until Bucky can see his face. Immediately, the annoyance prickling under Bucky's skin melts away when he catches sight of the two black eyes Tony is now sporting. Additional bruising runs down the left side of his face, disappearing into both the scruff of his beard and under his ear into his hair. Bucky crouches down, reaching out very carefully to cup the uninjured side of Tony's face. He sucks in a breath as he gets a closer look at the ugly bruising, which has to hurt no matter how brave Tony is trying to act.

"You should see the other guys," Tony says, trying to smile and then wincing.

"If I saw the other guys, I would shoot them," Bucky says, which isn't a lie. He picks up the ice pack he brought down with him and carefully sets it against the worst of the bruising, along Tony's left cheek. Tony doesn't try to squirm away, just slowly relaxes.

"It's really not that bad, Buck," he says. "I've had a hell of a lot worse."

"Is that supposed to be comforting?" Bucky demands. "Can't leave you alone for two days. Did you eat or sleep while I was gone?"

"I slept for three hours."

Bucky levels him with a glare. "The time you spent unconscious from a concussion doesn't count."

"Then no."

Christ. Tony Stark could drive a saint into insanity. All Bucky wants to do is throw Tony over his shoulder and carry him straight up to his bedroom, and then stand guard until Tony's eaten and fallen asleep. The funny thing is, Tony would probably let him do it. He would grumble a lot, pout and snark about overachieving mother hens, but he wouldn't really fight it the way that Steve used to. There are days when that still fucks with Bucky's head, but more and more he's coming to appreciate it. Appreciate Tony.

And maybe it's just Tony being kind, because Tony turns himself inside out to make the team happy. He goes out of his way to anticipate their needs and seems to consider it a personal failing if someone needs something and he's not ready for it (even though nine times out of ten, he fulfills the need in less than an hour no matter how much it costs). Bucky's almost positive that this is just one more way that Tony is accommodating him, like Tony's noticed how lost Bucky feels without someone to take care of and is stepping into the role even though he doesn't really need it, and Bucky is just pathetic enough to read too much into the situation and hope that Tony likes it too.

"Buck? You okay? Wait, how did your mission go?" Tony's voice, plus the touch of a hand over the ice, jolts Bucky away from his thoughts.

"It was fine," Bucky says, shaking his head. Way to drift off right in the middle of taking care of Tony. He lets go of the ice now that Tony has a hand over it and stands up. "Come on, get up. You're going to eat something, take the pain medication Bruce gave me and go straight to bed."

"I have work to do," Tony says.

"Is anything on your list urgent?"

Tony considers the question. "I have this one thing for Fury - "

"Fury isn't urgent. Up you get."

"Funny, I've been saying that for years but no one ever listens," Tony says, cracking a smile. He grabs Bucky's hand and lets Bucky pull him up, swaying just a little once he's actually standing. Bucky moves to stabilize him automatically, wrapping an arm around Tony's shoulders. Tony leans into him with a contented little hum, and they stand there for about a minute.

The moment is ruined when Tony's stomach growls.

"Let me guess, you haven't eaten either."

"Don't wanna," Tony mutters. "Food makes me nauseous." He puts his free hand over his stomach protectively, and Bucky's heart melts fast as the ice.

"How about soup?" he suggests. "Maybe from that diner around the corner that you like so much?" Tenderly, he brushes a strand of damp hair out of Tony's face. "I bet Steve would go pick it up for you. You'll feel better if you have something in your stomach."

Tony sighs. "Okay, okay, Daddy."

It’s clearly meant to be mocking, but the nickname jangles along Bucky's nerves in both the worst and best way; his eyes widen and so do Tony's, as the sincerity of the word catches up to them both. For a few tense seconds no one says anything. Bucky can see the way Tony’s mind is racing in the flutter of his eyelashes and the quickening of his pulse, mouth opening and closing with no words coming out. But he doesn’t immediately brush it off as a joke and in the end, Bucky’s the one who clears his throat.

“How about a shower while Steve’s getting the soup?” he says, deciding to put that aside for the moment for closer analysis when Tony isn’t standing less than a foot away. 

“Sure,” Tony says after a long pause. 

It’s the most agreeable he’s been in weeks and Bucky takes full advantage, ushering him into the elevator before he can gather himself enough to start protesting. Tony goes along with it, staring at the floor as Bucky taps out a quick text to Steve. He’s not at all surprised to get a text back less than a minute later: Steve is on his way out the door.

“Soup is incoming,” he says as the elevator doors open to Tony’s floor. There’s another awkward moment when they both step out: it only now occurs to Bucky that what feels natural, which would be hustling Tony into the bathroom and helping him peel off his clothing before pushing him into the shower, really isn’t. It’s way beyond what Steve would’ve tolerated, for one thing, and he’s pretty sure that guys don’t usually do that for each other in the twenty-first century. 

So for a couple seconds he actually thinks about waiting out here and letting Tony go shower alone, but then Tony glances up at him. There’s something vulnerable about the way that Tony sucks his bottom lip into his mouth and chews on it. Almost childlike.

And clearly the whole ‘Daddy’ thing is now fucking with his mind in a way that would probably outrage Tony if he knew. Still. Bucky can’t just walk away. Not now.

“Well, come on then,” he says, keeping his tone playful, and follows Tony into the bathroom. He switches the shower on automatically, even though the wait for the water to warm up is miniscule compared to what he’s used to, then turns to Tony.

Without being asked, Tony lifts his arms – though not as high as usual, leading Bucky to believe that his ribs probably took a bit of a pounding as well. The new bruising he finds when he pulls Tony’s shirt off confirms that. Man, he _really_ wants to have a few minutes alone with those idiots. It’s too bad that the Hulk and Hawkeye got there before him. From what Clint said, there’s not enough left of the would-be kidnappers to make a difference.

“It’s not that bad,” Tony says, catching where Bucky’s looking. “Really.”

“Yeah, I heard that enough from Stevie when he was a scrap like you to know that’s a lie,” Bucky says, thumbing open Tony’s jeans. He lets Tony wiggle those and his boxers off while he grabs a towel from the linen closet and sets it out. 

“I am not a scrap. You’re not allowed to compare me to you. That’s just unfair.”

Bucky just rolls his eyes. “Get in the shower, scrap.”

Tony pouts at him but obeys. Bucky leaves the room and catches himself leaving the door open a little bit. He frowns at himself. Okay, so he’s always had a little bit of a penchant for being a mother hen. But he’s only now realizing just how much of an extreme he’s taken to with Tony. Tony isn’t actually a child, he’s an adult who is perfectly capable of showering alone, yet Bucky’s leaving the door open like Tony might call out for help.

The water splashes in the bathroom and Bucky shakes his head. Still not the time to be dwelling on this. He heads into Tony’s bedroom and gets the bed ready, setting out a pair of pajamas and pulling the covers down and fluffing the sheets and putting the pain meds out with a glass of water. By the time he’s done, Steve is there with the soup and Tony’s out of the shower. 

Steve doesn’t stick around, which is probably a good thing because Bucky’s not sure if Tony would be okay with anyone else seeing how cute he looks when he shuffles out of the bedroom. He’s wearing the pajamas Bucky laid out for him and rubbing his eyes, obviously sleepy. Though he stops as soon as he realizes Bucky is watching. Typical Tony.

“I don’t want food,” Tony says. 

“Just a couple of spoonfuls.”

“You’re so annoying,” Tony grumbles, taking a seat at the table. He picks up the spoon and pokes at the soup.

“Do you want me to feed you?” Bucky asks. He’s done it before when Tony was overly tired and, before that word, he probably would’ve done it again. Now he’s not so sure.

Tony makes a face but lifts the spoon to his lips. He actually ends up eating the whole bowl of soup, shooting Bucky little glares the whole time like he’s daring Bucky to comment. Bucky just keeps his expression schooled into absolute innocence. 

When Tony is done, Bucky gives him the medication and the water and then leads him into the bedroom. JARVIS dims the lights without being asked. Tony gets under the covers and puts his head on the pillow, yawning. Bucky perches on the side of the bed, where he always sits until Tony falls asleep. Because otherwise, Tony has a terrible time drifting off and will toss and turn for hours. Sometimes, if he’s having an especially hard time, Bucky will rub his back or his feet and that puts him out like nothing else.

“Night…” Tony mumbles, his voice trailing off, and there’s definitely room for something there at the end of that sentence. 

Bucky’s heart twists, looking down at him. He’s not sure what this is, or what it means, or if he’s completely misunderstood what might be happening. Actually, he’s not even sure he understands what might be happening. He waits until Tony’s breathing evens out and he starts making those adorably snuffly sounds that means he’s in a deep sleep, and then he carefully gets up and tiptoes out of the room.

He’s got some research to do.


	2. Chapter 2

Bucky gives it a week. He does some research on the side – with the safe search _on_ , thank you JARVIS: some of the things that Bucky saw in his first search, he can never un-see. And if Tony has an interest in making this sexual, it’s never going to work because Bucky definitely, 100% does not feel attracted to Tony Stark – and compiles a list of things that Tony may or may not be interested in trying. That is, if Tony is interested in this at all and Bucky hasn’t completely misread the situation, which is also a distinct possibility.

That’s why he doesn’t bring it up right away. What he and Tony have is nice. None of the other Avengers are going to let Bucky fuss over them like that. Natasha would stab him the first time he tried. Clint would turn it into a joke. Thor would just be confused. Bruce would just raise an eyebrow in that way he has and make Bucky feel stupid. Sam would either treat it like a joke, or call up Bucky’s therapist. And Steve…

He suppresses a shudder. Steve would get pissed. Except he’d get all passive aggressive about it because he wouldn’t want to admit that he was mad, which would be even worse than if he was just flat-out angry. Bucky’s had enough of sideways glares and muttered comments and forced nicety to last him ten lifetimes. He knows better than to ever even suggest that Steve needs to be taken care of in any way, shape or form.

So he waits to see if things can go back to normal between him and Tony before he crosses that line, but they don’t. Something’s noticeably different now. It’s not awkward per se, but there’s definitely a hint of something _more_ that hangs over every interaction. Bucky hates it. He wants to be able to pull Tony into a hug or shovel food into his mouth or strip him down and toss him in the shower without second-guessing himself or Tony about it.

On Saturday morning, he makes his way down to the shop with the list. It’s not always great to interrupt Tony’s private workshop time, but it’s also the most secure place in the tower so it's the best place for their conversation. Bucky waits until Tony lifts his head and actually acknowledges him, which takes about twenty minutes, and then sets the list down in front of him. Tony looks down, but his only reaction is the slight widening of his eyes.

“J, lockdown,” he says over the music, voice blank.

The glass windows of the workshop go dark. The music goes off, but Bucky is positive that no one can hear them. He takes that as his cue to pull up a chair since Tony’s immediate reaction wasn’t to throw him out. He sits quietly as Tony reads through the list – it’s a comprehensive one. When he feels that Tony’s had the time to read and absorb it all, he clears his throat.

“My only caveat is that I’m not interested in sex. So if that’s what you need, I’m not your guy.”

Tony snorts. “Because everything I do has to be sexual?” he asks, wiggling his eyebrows, but Bucky can detect a note of hurt in his voice.

“No, that’s not what I meant. I made the mistake of looking some things up without asking JARVIS to filter the results.”

“Ooh, bad idea,” Tony mutters, flipping the page over. The backside is blank, so he looks back up at Bucky. The tips of his ears are pink, and as Bucky watches the blush slowly travels into his face, warming his cheeks. It’s the first time he’s ever seen Tony blush, and it’s _adorable_.

“Yeah, not my best moment. Once I figured that out, though, there was lots of information to be found.” Bucky taps the paper meaningfully. He’s not gonna let either one of them hide from this. They go into it with eyes wide open or not at all, but there’ll be none of this dancing around bullshit that Tony is so good at. 

Tony nods, and then he mutters, “I’m sorry.”

It’s so far from what Bucky expects that he just frowns. “What?”

“I shouldn’t have – I went too far.” He sets the paper down, fingers trembling a little.

Bucky gets it then. “Oh, sweetheart, no,” he says, putting a hand over Tony’s. “You didn’t pull me into anything, if that’s what you’re thinking. If anything, I pushed myself onto you. Steve likes to call me the biggest mother hen that ever lived in New York, and he’s probably not that far off. I’m used to takin’ care of someone, but Stevie doesn’t need me anymore. You were the only one receptive to that. I guess the fact that you can’t remember to feed yourself helps.”

“I eat,” Tony says haughtily.

“Yeah, when I feed you,” Bucky says with a grin. They both glance down at the list as the words sink in. ‘Hand and spoon feeding’ is written right underneath ‘bottles’ and 'sippy cups'. Bucky is fine with all of the above, frankly.

“It’s weird,” Tony says.

“I’m over ninety years old. I have a metal arm. I live with a god, two assassins, a guy who flies with metal wings, a guy who turns into a green rage monster, Captain America and a billionaire,” Bucky says dryly. “Tell me what _isn’t_ weird about our lives.”

That, at last, gets Tony to smile faintly. “Fair point, I guess. I didn’t think… No one’s ever known. I don’t do it very much.”

“’It’ being age play?” Bucky asks, wanting to put a name to it. Those two words make Tony’s blush deepen, but he nods slowly. Bucky nods too, and says, “And I’m guessing you’re pretty little, because you don’t seem to mind when I feed you or help you take your clothes off. There’s a list of ages at the bottom. Could you point to the one you think you are?” He softens his tone with that last question, turning it into something coaxing.

Tony responds beautifully, moving a still-shaking hand to the bottom of the page. The ages are pretty rough based on what Bucky read online, especially since it seems like people can have different ages depending on the day, but he ordered them 0-2, 3-4, 5-7, 8-10, 11-13. He only added the older ages on to make Tony feel better because he’s positive Tony is below five. 

After a very long moment, Tony points to the 3-4. “That one.”

“Are you sure?” Bucky asks, keeping his voice gentle. “’Cause I won’t be upset if you’re even littler than that, Tony. I wouldn’t complain about having a cute baby I could carry around.”

Tony’s finger slides down a quarter of an inch until it’s resting on the 0-2. He doesn’t say a word, but his face is tomato red.

“Okay. Okay, that’s good. I’m proud of you,” Bucky says, meaning it. This can’t be easy. He squeezes Tony’s hand. “And can you tell me if there’s anything on the list you don’t wanna do?”

Tony shakes his head without even looking at the list and Bucky figures he’s had enough for the moment. To be fair most of the stuff on the list is geared towards a very young little, so Tony probably does have some interest in all or most of it. Which Bucky had kinda figured from the start, considering that Tony hadn’t ripped the list up as soon as he saw what was on it.

“We can look at it again later. Can I hug you right now?”

The jerky nod he gets in response makes Bucky move fast, standing up and pulling Tony into his arms. He hugs Tony as tightly as he dares, not really sure if he has an adult in his arms or a baby or something in between. Either way, it doesn’t matter. This is a step in the right direction.

They don’t talk about it anymore that day – Tony goes straight back to work after the hug, and Bucky takes a seat on the couch and plays with Dummy for a while – but they do revisit the list, mostly because it turns out that Tony doesn’t have very much in the way of age play stuff. He has a small pack of adult diapers, an old pacifier, a Bucky Bear (which Bucky can’t help smiling at), and a few toys.

“I’m surprised you have the diapers,” he admits, playing with the Bucky Bear.

“I never really wore them. Pepper refused to let me have them in the workshop,” Tony says absently, scrolling through a long list. “That’s what I originally bought them for, anyway. The you know what came later, and then it seemed stupid to wear them by myself.” He stops, shunting an aside glance at Bucky. “Are you sure…”

“Yes, I’m sure,” Bucky says without even looking up, having answered a variation of this question about ten times now. “I used to change my kid sister’s diaper.”

“This is a little different.”

“Not to me. Besides, you don’t wanna know what I’ve seen. This is nothing.” It takes effort not to let his mind fall into those dark memories. The things he _did_ to people. More than blood covers Bucky’s hands at this point.

Tony puts a hand on his arm. “You okay?”

“Yeah, fine.” Bucky inhales deeply and exhales to the count of seven, just like his therapist taught him, and smiles at Tony. “You ready to place an order, kiddo?”

“Just about.”

The day the stuff arrives, it’s placed on Tony’s floor by mutual, unspoken agreement. Natasha and Steve are too frequent visitors to Bucky’s floor, often without warning. Tony takes a diaper, jeans with an elastic waist, and a blue t-shirt into the bathroom to change. Then he walks out, smiles at Bucky, and announces that he’s heading down to the workshop.

Which, huh. That’s not exactly what Bucky expected.

He watches Tony go with a frown. They didn’t really talk about whether Tony would go down to the workshop while they were age playing. Actually, they didn’t really talk about how this would go at all. Suddenly, he has the feeling that they probably should have. Because as far as Bucky’s concerned, it’s not really age playing if Tony does exactly the same thing as always, is it? The internet had talked about a headspace, but Tony hadn’t seemed any different from how he usually was when he left.

“I think we’re doing this wrong,” he mutters at the empty room.

But it doesn’t seem right to follow Tony down immediately, either. So Bucky joins the team for an early lunch and then spends the afternoon whipping Clint’s ass at Mario Kart – and it just kills Clint that he’s being beaten repeatedly by Princess Daisy, which just makes it that much more fun. Then Steve wants to spar for a while, and Natasha ends up wandering in while they’re at and they turn it into a ‘every man for himself’ spar until Bucky and Natasha team up to bring Steve down.

All told, it’s close to 8pm before Bucky finally gives in and goes down to the workshop. As always, Tony is hard at work. This time he’s bent over some wiring. Bucky waits until the sparks stop flying before he clears his throat. Tony’s head pops up. He looks a little surprised to see Bucky standing there, but smiles.

“Hey. What’s up?” he asks, wiggling a little in his seat.

Bucky recognizes that wiggle; it tugs at a memory buried way deep of his sister, needing a change but so involved in something that she thought was fun that she didn’t want to admit it. And it hits him then that they’ve definitely done this all wrong, because Tony shouldn’t be down here all by himself in a diaper. They should’ve talked about what would happen when they wanted to age play.

But that can wait until tonight, or even tomorrow if necessary. Right now, he has a baby to care for.

“You need a change,” Bucky says. 

Tony’s eyes widen. “No I don’t.”

“Really.” Giving him ample time to pull away, Bucky walks up to him and slides a hand down the back of Tony’s jeans and diaper. His fingers encounter wetness, which isn’t surprising: now that he can see Tony’s lower half, he realizes that Tony’s wet through to his jeans without even realizing it. 

Tony’s flushed with guilt when he looks at Bucky again. “I was working.”

“Yeah, no. Come on, scrap.” He takes Tony by the hand. Tony doesn’t resist, meekly following him into the elevator. With JARVIS in control there are no interruptions, and they get to Tony’s floor without incident.

There’s no point in trying to change Tony when he clearly needs a shower, so Bucky leads him into the bathroom. Tony stands silently as Bucky stripes him, though he squirms a little when Bucky removes the diaper. There are red, raised bumps between his thighs and around his crotch that look raw and painful. Diaper rash hasn’t changed in seventy years, that’s for sure. 

“It hurts,” Tony says, very softly, and all of Bucky’s frustration melts away instantly. This is both their faults, really. Bucky should’ve known better than to leave Tony down there all day, and Tony should’ve known better than to sit for hours in a wet diaper. Frustration doesn’t solve problems, and right now Tony needs him.

“Aw, baby, I know it does,” he murmurs, pulling Tony into a hug. “We’ll figure this out, okay?” He’s gonna have to be more strict with Tony. The realization calms Bucky in a way. This is what Tony needs from him: affection, but also a level of care that no one else can provide. Tony won’t be able to go into the workshop when he’s truly little anyway, but taking on this role also means limiting his time down there when he’s wearing a diaper. Bucky thinks he can do that, and after this he might not even get much of a fuss.

Tony hugs him back desperately, fisting his hands in Bucky’s hoodie, making these little gaspy breaths that sounds like he’s trying not to cry. Bucky cups the back of his head. “It’s okay, sweetheart,” he whispers. “Daddy’s gonna give you a bath and make you all nice and clean. Then we can have some dinner. That sound alright to you?” He waits for Tony’s small nod before switching on the water.


	3. Chapter 3

It takes a little trial and error, but eventually they come up with a list of rules that they can both agree on. Bucky prints the list out and puts it on Tony’s fridge just because that makes it seem more official. Tony makes fun of him for it, but Bucky catches him touching the paper and smiling when he thinks no one else is around, so he doesn’t care. Chances are the rules will change as they continue, but he’s okay with scratching things off the list and writing in the new rules no matter how much Tony cringes.

Besides, a physical reminder of the rules never hurt anyone, even though they’re pretty simple: Tony’s time in the workshop is limited when he’s got a diaper on, he’s not allowed in the workshop without supervision if he’s in his little headspace (and no, JARVIS does not count as supervision), bedtime is 8pm when Tony’s little, they’re going to aim for one day a week if possible, etc… They even have agreed-upon safe words, including words they can use if one or both of them needs to age play.

It’s so safe, healthy and consensual that it’s almost frightening when Bucky stops to think about it. His therapist would be so proud.

first when they age play, they don't do anything more than watch movies and play with some Legos and read together. Bucky still feeds and bathes Tony and puts him to bed because he’s been doing that for months, but otherwise they ease into it. Diapers and bottles are introduced slowly, but Tony takes to them with ease and even suffers a couple diaper changes with no more than a flushed face.

Bucky tries not to dwell on how long Tony’s been craving something like this. It makes him want to punch things if he thinks about it for too long. To see this guy – this guy who is, at the heart of things, someone who just wants to do right and be told he’s done good – be ignored at best and outright vilified at worst is infuriating. He tamps that down, though. It’s not what Tony needs right now.

Despite the fact that they’ve age played a few times, Tony never once cries or throws a tantrum or does anything other than what Bucky wants or needs him to do. So it’s a little jarring to have a morning where Tony is definitely sunk deep in his headspace. He’s got both arms wound around Bucky’s neck and his face tucked into Bucky’s neck. He’s not crying, but he’s as close to it as Bucky’s ever seen him, little tremors running through him.

“It’s okay, doll,” Bucky says for the thousandth time, pacing back and forth. He’s realizing they might need to work a rule about sleep into the list. Part of the problem is that Tony’s been up for days at this point and he’s so tired he’s reached the point where he can’t sleep. Rocking, singing, a warm bath, rubbing Tony’s back and feet… none of the tried and true methods work.

“Dada,” Tony whimpers around his pacifier, slurred and teary, and Bucky tries not to wince. Shit, the kid’s breaking his heart.

“How about a bottle?” he suggests, heading into the kitchen, only to realize that Tony’s fresh out of milk. He stares into the empty refrigerator in dismay, knowing for a fact that there’s nothing in his own fridge either. Most of the Avengers don’t bother to keep food on their floors because the communal floor is always so well-stocked.

He taps his fingers against the door. He and Tony talked a little about the rest of the team knowing. Tony made it amply clear that he didn’t care one way or the other, seeming to think that nothing stayed secret in the tower for long (which wasn’t wrong: the Avengers were a bunch of gossips as far as Bucky was concerned) and that the team would probably just think it was a weird kink. He said that with the worst self-deprecating smile Bucky had ever seen, like it was okay the team should think so low of him, which was a problem in itself that Bucky’s not ready to address. Yet.

So it’s really on Bucky at this point, and in most other circumstances he wouldn’t, but Tony is whimpering in his ear and he can’t think of anything other than a bottle and getting milk delivered will take too long and water isn’t going to cut it when Tony hasn’t eaten in hours; warm milk will at least fill his belly a little and might help calm him down. It’s with that thought in mind that Bucky picks up an empty bottle, swings around and heads for the elevator, snagging Bucky Bear on the way by and pressing him into Tony’s arms. 

The whole team is clustered around the table because Bruce is cooking breakfast. Bucky ignores them and heads straight for the refrigerator. He’s inordinately relieved to see the three brand new jugs of milk and grabs one, snapping the cap with ease. He fills the bottle most of the way with milk, well aware that Tony has passed sniffing and is now crying quietly into the hood of his sweatshirt.

“Let me,” Natasha says, appearing at his side. Bucky doesn’t jump only because he’s trained himself not to. She smirks at him anyway and plucks the bottle out of his hand. 

“Don’t use the microwave. It’s too hard to control the temperature. Put hot water in a bowl,” Bruce says without looking up from where he’s concentrating on a mountain of scrambled eggs. “Then stick the bottle in and let it heat that way.”

“Got it. Out of the way.” Natasha pokes Clint in the side until he shuffles out of the way, allowing her to retrieve a bowl. Clint just grumbles something unintelligible and huddles over his half-empty coffee mug.

Bucky eyes them, cupping the back of Tony’s head protectively. Steve is staring at them with dumbfounded expression, but Natasha, Clint, Thor, Bruce and Sam are carrying on like it’s business as usual. It doesn’t take long for the obvious to sink in, and Bucky sighs.

“You all knew.”

“You’re not subtle,” Sam says from the table.

“I didn’t know,” Steve says. “Wait. Know what? What is this?”

“Steve’s just oblivious,” Sam mouths at Bucky from behind Steve, and Bucky has to bite back a smirk.

“It’s called age play,” says Bruce, straightening his glasses. “Non sexual, I’m guessing, right?” He glances at Bucky, who nods. “It’s a coping mechanism, basically. Some people like to deal with the stress of adult life by reliving certain aspects of their childhood. They find it relaxing to not have to worry about daily stress. When that happens it’s called a headspace, which is what Tony is in now. And some people, like Bucky, find caring for those people to be very comforting.”

“Because Bucky needs to be needed,” Clint mutters, throwing back the rest of his coffee. Bucky throws an orange at him. Clint catches it without even looking, the little shit.

“Anthony is quite cute this way,” Thor says, propping his chin on one hand and smiling. “He clings to you very tightly.”

“He can’t sleep,” Bucky says, moving past surprise at the reminder of their current situation. He hefts Tony’s slight weight a little higher, grimacing at the feel of something slimy on his neck when Tony noses in closer. 

Surprisingly, Clint nods knowingly. “I’ve been there. You get to a point where you’re so wound up and there’s so many thoughts in your head that you can’t shut your brain up and you can’t relax. Of course, I don’t usually put on a diaper during those times.” The words could’ve been sharp or mocking, but his tone is more akin to a gentle tease.

Natasha snorts. Clint frowns at her. She smirks. He glares. Bucky glances back and forth between the two of them and decides that it’s probably better not to know.

“It seems kind of… weird,” Steve says.

Until that point, Bucky’s not sure if Tony was aware of the conversation or not. But Tony tenses a little at those words and Bucky scowls. “It’s not weird,” he snaps, pressing a comforting kiss to the top of Tony’s head. “I get to take care of someone and Tony gets to sit back and let me do it. It’s no weirder than BDSM or something like that.”

“BDSM involves orgasms,” Bruce points out. Everyone stares at him. His face goes a little pink and he bends over the frying pan.

“Right,” Bucky says into the awkward silence, figuring that’s something else he doesn’t need to know. “We’re not hurting anyone and we both like it, so it’s fine.” He stares hard at Steve, hoping that Steve – and the rest of the team, for that matter – will take it for the silent warning that it is: a warning that if Steve says _anything_ negative about this to Tony, Bucky’s going to kick his ass.

“Sam and JARVIS will help him google it,” Natasha says, plucking the bottle out of the bowl. She tests the milk against the inside of her wrist and apparently deems it fine because she hands the bottle to Bucky. “It’ll be fine. Go take care of Antoshka.” Her smile is genuine this time, with an edge of softness that Bucky doesn’t typically see from her.

“Google it with the safe search on,” Bucky says, and the second Steve’s eyebrows draw together, he knows he shouldn’t have said it. Telling Steve not to do something is unquestionably the best way to make him do it, which basically means that Steve is about to see some things that he probably does not want to see. At least he probably won’t make the mistake of googling ‘my friend call me daddy’ without the safe search on like Bucky did.

“Who knows, perhaps you will find something that you like,” Thor says, clapping Steve on the shoulder so hard that Steve buckles under the pressure. 

“I doubt it,” Steve says, but he’s flushed and won’t meet Bucky’s eyes and that’s – huh. That’s interesting. Bucky eyes him, half-tempted to push because, now that he thinks about it, Steve definitely has some mother-hen tendencies of his own, but Tony chooses that moment to let out a choked little moan that sounds a lot like a prelude to a full-on tantrum. 

He heads into the living room and takes a seat on the couch, supporting Tony with one arm and hooking the pacifier out of Tony’s mouth with his pinkie. Tony gets the chance to draw in exactly one breath before Bucky pops the nipple of the bottle in, squeezing the plastic sides a little to let him get the taste of the milk. For a solid second Tony gives him a betrayed look, as though to ask why Bucky took away his opportunity for a tantrum, but then he settles down to drink.

“You’re good with him.”

Bucky glances up as Bruce sits beside him. Bruce is smiling. He starts to lift a hand and pauses, flicking his eyes towards Bucky to ask permission, which Bucky grants with a nod, and then reaches out to Tony. He’s very gentle as he slides his fingers into Tony’s hand. Tony grabs on with surprisingly strength, other hand holding onto his Bucky Bear.

“He’s little,” Bucky says, hearing a hint of defensiveness in the words. 

“I wasn’t saying that in a bad or mocking way. Not very many people are good with Tony.”

“Not very many people try.”

“True,” Bruce agrees, grinning when he wiggles his finger and Tony’s grip tightens. “But there’s also not many people who could talk Tony into letting himself be this vulnerable. I can think of two other people, maybe three. I hope that you’ll exercise caution.”

“Is this the shovel talk?” Bucky asks, suddenly recognizing this chat for what it is. “You gonna set the Hulk on me if I fuck up?”

Bruce tips his head, the slow curl of his lip the only sign that he’s displeased Bucky would think that. “No. I’m just not used to people knowing what Tony is worth, that’s all. Sorry. I guess it’s not really my place to say this to you.”

“It’s fine,” Bucky says quickly, both because Bruce is one of Tony’s closest friends and because Tony is finally starting to fall asleep and Bruce standing up will ruin that. “I get what you’re saying. I didn’t start off intending for things to end up like this. It just… happened. But once I realized it was a possibility, there didn’t seem to be any point in not doing it.”

Because he loves this. He can admit that to himself. Looking down at Tony, whose eyes are half-lidded as he valiantly tries to stay awake long enough to finish his milk, Bucky’s in love. Here at last is someone who really does need him, who can be an outlet for all of the protective tendencies Bucky’s never been able to smother, who isn’t afraid of him, and who needs the affection just as much as Bucky needs to give it. 

“I’m glad that you’re both happy,” Bruce says sincerely. “The Bear is a nice touch, by the way.”

“It was Tony’s actually. He already had it.”

“Guess it was fate,” Bruce whispers, because Tony’s eyes are sliding shut. They both freeze, not daring to move until Tony’s breathing deepens and his grip on both the bear and Bruce’s hand go slack. Bucky exhales and removes the nipple of the bottle, setting it aside. Finally, Tony’s asleep. But even after all that, he still wouldn’t trade this. Not for anything.

He looks down at Tony again, feeling happier and more peaceful than he has since the first time Steve dragged him into the tower. “I guess so.”


	4. Chapter 4

Bucky is sitting on the couch watching television (on Tony's floor, not his own. There's just something about Tony's space that's infinitely more comfortable than his own, and he knows for a fact that Tony doesn't mind - if anything, though he'll never admit it, Tony likes having Bucky around) when the elevator doors slide open. And if it were possible for sliding doors to slam, then Tony would be doing just that right now. Bucky raises his eyebrows as Tony storms out of the elevator and into the kitchen, muttering under his breath. 

"Something wrong?" he asks when it becomes evident that Tony's not planning to share his grievances. Almost immediately, like he was just waiting to be asked, Tony's head pops around the door and he glowers at Bucky.

"Your best friend is an asshole."

Ah, Bucky should have guessed what this was about. He lets out a sigh and pinches the bridge of his nose, wondering what the hell Steve's problem is. Ever since the team found out about their age play, it's like Steve has been knocked off his usual pace. He fumbles everything he says and nothing comes out right, and most conversations between him and Tony now end with them snapping at each other. And Bucky can tell that Steve's not doing it to be mean, but Tony doesn't see it that way. He's not even angry about it. No, it's hurting Tony's feelings, though that's something else Tony would never admit.

"I don't disagree," Bucky says quietly, though he thinks there's more to the situation than just Steve being an asshole. Evidently, since those two idiots aren't going to work it out themselves, it's up to Bucky to say intervene before their supposed leaders end up in a huge feud. Just the thought if it is enough to make a headache start up somewhere behind Bucky's eyes.

"Stupid Rogers," Tony snarls under his breath, banging glasses around. "If it bothers him so much, why doesn't he just come right out and say it?"

Apparently the intervention needs to be sooner rather than later. Bucky gets up and walks into the kitchen, coming right up behind Tony before Tony even realizes he's there. He wraps both his arms over top of Tony's, trapping Tony in a hug. "Hey," he says, very softly, right into Tony's ear. "To hell with Stevie, okay? This is between you and me, babe, no one else. Don't let what he does or doesn't say affect what you want."

Tony remains tense for several seconds before he slowly starts to relax. "He's an idiot," he grumbles, though half-heartedly.

"Yes, he is," Bucky agrees, and he is going to kick Steve's ass for this. "But you're still my little baby, right?"

The back of Tony's neck turns pink. So do the tips of his ears. He squirms a little, not really trying to get free, just testing Bucky's hold. Bucky keeps a firm grip, and eventually Tony subsides entirely. The tension drains out of him, leaving Bucky supporting his whole weight. Only then does Tony nod, just once, and so slight that Bucky would've easily missed it had he not been watching Tony so closely. He can't help the smile that tugs at his lips even as he easily lifts Tony up into his arms. Tony squeaks in surprise, automatically throwing an arm around Bucky's shoulders.

"Hey," he protests, though he doesn't actually make any move to get down.

"You need a nap," Bucky says, carrying him into the bedroom.

"We're not age playing," Tony complains.

"No, but I can still see the signs of a sleepy boy all the same." He sets Tony down on the covers, knowing he's right when all Tony does is flop over and grumble while Bucky pulls the blankets up around his shoulders. He sits on the edge of the bed beside Tony until Tony's passed out, sprawled on his belly with his face buried so deep in the pillow that you'd think he couldn't breathe, and then he goes to find Steve.

It's not hard, as it turns out. Steve isn't exactly hiding. He's in the communal gym, beating up on a punching bag. Bucky hangs back, staring critically at his back. Natasha's told him stories about what Steve was like when he first woke up from the ice, about how Steve used to spend hours in the gym until even the highest quality punching bags broke under his fists. Eventually Tony came up with a punching bag that could withstand even the worst of Steve's anger and frustration, but by then Steve was adapting to the modern world and had less need of them. Bucky hasn't seen it this bad for a while.

He lets it go on for a while until there's a natural break, a moment when Steve stops to wipe the sweat out of his eyes, and then he says, "What's with the attitude, punk? You're upsetting Tony and I don't like it."

"What, you fight his battles now?" Steve grunts, aiming a right hook at the bag.

That gets Bucky's hackles up, and he stalks across the floor. "When it comes to something like this, yes, I do," he says. "He's my boy and it's my job to protect him. Even if that means I have to point out what an asshole my best friend is being. We're not hurting anyone, Steve. You know that. I know that JARVIS helped you with the google searches. Tony gave him some sites to give you."

"It's weird," Steve mutters.

"That's your excuse? That it's weird? Please. I know you have to have something better than that."

Steve mumbles something unintelligible, turning away like they're done with the conversation. Angry now, Bucky grabs at his shoulders. He's unprepared for Steve to twist and shove him away. Bucky stumbles but catches himself just in time for Steve to get in close.

"I don't know!" Steve yells in his face. "I don't know, okay? Something about it bothers me, but I don't know why." He's breathing hard, his chest heaving as he gulps in air. All at once, the fight seems to drain out of him. His shoulders slump and he half-turns away, running a hand through his sweat-soaked hair. "I just... whatever it is, I keep feeling this way every time I see you and Tony and I hate it."

Bucky stares at him in astonishment, because he _recognizes_ this. "Steve," he says, very slowly, "are you jealous?"

Steve blinks. "What? No."

"Yes you are. You totally are. You're jealous of me and Tony," Bucky says, the puzzle pieces falling into place. "Wait. Are you jealous of me or of Tony?"

A scowl crosses Steve's face and he folds his arms. Despite the fact that he's acting like a petulant two-year-old, Bucky suspects that he's not jealous of Tony. It's just not in Steve's nature to give up that kind of control. God knows that Bucky used to see the evidence of that every damn day when Steve used to act like Bucky was trying to set him on fire instead of trying to stop him from getting into fights on a regular basis. So that means that Steve is jealous of Bucky, which makes a lot more sense: Steve definitely has some papa bear tendencies of his own. 

"Just forget it," Steve says, voice sharp.

"Absolutely not. You think I'm going to just let this go? I know what you and Tony are like. You'll keep needling at each other until it blows up in a fight. And sure you'll eventually make friends again, but in the meantime I'm the one who's going to be stuck dealing with the fall-out on both sides." Bucky shakes his head. Then, well and truly fed up, he punches Steve in the shoulder. Hard.

"Ow! Buck, what the hell -"

"Why didn't you just ask Tony and me if you could join in?" Bucky snaps.

"What?"

"I don't know if Tony would be okay with it now, considering your attitude for the past two weeks, but Steve... for fuck's sake, Tony _adores_ you. He wants your approval so badly that it hurts sometimes. When you tell him that he's done a good job, it's like looking at a five-year-old that just received their father's praise for the first time ever." And no, that doesn't sting. Not even a little. Bucky knows very little about Tony's past, but he knows it was complicated and painful and Steve is the living personification of those feelings. 

Steve stares at him. "No he doesn't."

"You could ask anyone else on the team and they will tell you that yes, he does," Bucky says.

"I didn't know that."

"That's because you don't pay attention," Bucky says flatly. These two idiots. How the hell Bucky got stuck with them, he has no idea.

"Hey, that's not true," Steve says defensively.

"Uh, yeah it is. You didn't even know you were jealous!"

"I am not - " Steve stops, apparently realizing that he's yelling again, and takes a deep breath. He holds it for a few seconds, then exhales. "Maybe I was a little jealous," he admits. "I'm sorry I was taking it out on Tony. I shouldn't have. I'll apologize to him the next time I see him."

"That's it?"

"What else do you want me to say?"

"I want you to talk to Tony about joining us."

"Tony would never go for that."

"I hardly think you're the master of knowing what Tony wants," Bucky points out. Maybe he's pushing it a little too much, but he thinks this would be good for both Tony and Steve. Tony would finally have the attention of the one person from whom he's most wanted it, and Steve would have a little one to help care for. Bucky pictures them working together to care for the baby. He and Steve have always worked well as a team, and there's no doubt in his mind that Tony would flourish under the attention and love of two people.

Steve sighs. "I just - I don't know if I can do that," he says. "It seems like a lot. Not the work, just... everything else."

It's never seemed like a lot to Bucky. Actually, it's the opposite: caring for Tony is far and above the easiest thing Bucky has ever done. But he concedes the point, not wanting to push too hard, and nods. "Fine. Think about it. But either way, you need to change your attitude. Next time you make Tony cry, I'm going to kick your ass."

A look of horror spreads across Steve's face. "I made him _cry_?"

"Yup," Bucky says with a smirk, figuring Tony will eventually forgive this slight to his honor. It'll do Steve good to think on the fact that he can't just act like a little shit with no consequences.

He starts to re-think that decision when, three days later, Steve shows up with a golden retriever puppy and an apologetic look. 

"Tony, I'm sorry," he says, very earnestly. "I didn't mean to be an ass about you and Bucky age playing. If it's something that you guys enjoy, it's fine by me."

"It's okay," Tony says, already entranced by the puppy. "Is that...?"

"He's for you. Every boy needs a dog."

Tony's eyes go a little wide and round when the puppy licks his hand, and Bucky can pinpoint the moment when he falls in love. 

"I hate you," he mouths at Steve from behind Tony's back, already imagining the additional chaos that this is going to add to their lives. Dealing with a fussy baby at 3am is bad enough. Dealing with a fussy baby _and_ a puppy is going to be more than Bucky can tolerate. Steve just gives him a slow smirk when Tony's not looking.

"So does this mean that you're finally going to join us?" Tony asks, kneeling down on the ground, and both Bucky and Steve stare at him.

"What?" Steve asks weakly, and then sputters, "You told him?" at Bucky.

"Please, Steve. You guys are like this," Tony says, crossing his middle finger over his index finger. "And you're just as much of an overbearing mother hen as Bucky; you're just not as obvious about it because you don't know what to do with yourself. I kinda figured from the get-go that if I got one, eventually I'd end up with two." His smile turns a little self-deprecating. "I know it's not exactly ideal, and you guys could get a way better little than me. If you wanted someone else, I would understand."

"Tony," Bucky says, heart aching. He knows that this is legitimately how Tony feels all the time, always thinking he's not good enough, but it still hurts to hear it said so matter-of-factly.

"No way," Steve says, cutting him off. "Tony, you're an adorable baby and I would be proud to call you mine. But..." Here, he hesitates. "You guys have this thing. I don't want to intrude on your relationship."

Tony looks at him sideways before rolling his eyes, pulling the puppy into his arms and nuzzling it. "J, teach the old man over there about this new fangled thing we have called polyamory," he says, standing up again. The puppy whoofs and wiggles all over, obviously overjoyed to be in Tony's arms, and Bucky catches sight of the soft smile on Tony's face right before Tony ducks his head and buries his face in the puppy's fur.


	5. Chapter 5

"Okay. So we've got our volcano all finished and everything's finally dry. The last step that we have to do," Bruce says, "is add the baking soda. But before we do that, we're going to pour in some vinegar. I think we should color it first to make sure that it really looks like lava. What do you say?"

Tony nods vigorously. "I do!" he cries, holding up his hands. "I do, Uncle Bruce?"

Bruce smiles at him. As far as Bucky is concerned, it's pretty hard not to. Tony looks _adorable_ in the light green onesie that Natasha bought for him, the one with the words 'little scientist' written across the front in black. He's also wearing an over-sized white lab coat and a pair of Bruce's goggles, pushed up onto his forehead. His hair sticks up above the goggles in curly tufts.

"How about you put in the coloring?" Bruce suggests, pointing to the range of colors. "And then Uncle Clint can pour the vinegar into the volcano. I think that's a good compromise, right Clint?"

"Sounds good to me. This is gonna be the best volcano ever," Clint says, ruffling Tony's hair gently. "What do you think, squirt? What color should our lava be?"

Instead of answering, Tony just sticks his fingers in his mouth and blinks up at Clint. From where he's sitting with Steve and Natasha, Bucky has to hold back a sigh. It didn't take long for all of them to pick up on a particular problem of Tony's: when he's little, he never wants to share his opinion. He always wants to do whatever everyone else wants. And the handful of times that anyone's tried to coax him into giving his opinion usually ended in confused tears. It's a habit they're all trying to break him of, but asking an open-ended question like that isn't going to get them anywhere. 

Clint seems to realize his mistake, covering it with a grin. He grabs one of the colors and holds it up. "How about purple?"

Tony's eyes flick to Steve and Bucky, looking for a hint. Steve shakes his head just a little, so Tony turns back to Clint and, around his fingers, says, "No!" 

"Blue?"

"No!"

"You're right." Clint nods, incredibly serious. He picks up another color and acts like he's unscrewing the top as he says, "Clearly, the lava should be green!"

"No!" Tony chirps again, starting to giggle at Clint's exaggerated motions. 

"How about orange?"

"Noooo," Tony whines. He's not even looking to Bucky and Steve now, too focused on Clint.

"Yellow?"

"That one!" Tony says, finally pointinf to the one remaining color on the table. Clint pretends not to see it, picking up random objects like a pen or a set of beakers and suggesting them as colors until Tony's shrieking with laughter. 

Bucky can't help a grin, especially when Clint grabs a squeaky toy and makes the mistake of actually squeaking it. Howl, who has been sleeping peacefully under Steve's feet, gets in on the action then, scrambling across the floor while barking and then trying to jump up on Clint. Clint stumbles back and slips, going down hard on his butt, the squeaky toy bouncing out of his hand. Howl scrambles after it and Tony's giggles almost immediately turn to wails.

"Uh oh," Steve says, jumping up. He hurries over to Tony, scooping the baby off the ground. "Hey, it's okay, Howl was just playing and got carried away. Uncle Clint is fine," he soothes, patting Tony's bottom comfortingly. 

"Papa!" Tony wails. "Dada!"

Bucky _knew_ they should've waited until after Tony's nap to do this volcano, but his suggestion had been out-voted by Clint and Natasha. And now they have a cranky, over-tired baby to contend with. He gets up and joins Steve, allowing Tony's hand to grab onto his shirt. "Shh, baby boy," he murmurs, leaning in to press a kiss to the side of Tony's head. "Papa and Daddy are right here. You're okay."

"Sorry," Clint says. "I didn't mean to upset him." He gets up, wiping his hands on his jeans. "Hey Tony, bud, look. I'm fine! And Howl's fine too." He bends down and scoops the puppy up into his arms, lifting him up until he's on par with Tony's face. Tony stops crying and stares at the two of them, still sniffing, right up until Howl drops the toy and goes for Tony instead. He enthusiastically washes the baby's face with his tongue until Tony starts to giggle again. 

"See? I told you the puppy was a good idea," Steve says, trying not to grin.

"You're the one who gets to give him a bath tonight," Bucky says, rolling his eyes. But he can't even be that angry. This is only the second time that Tony's been able to spend more than half a day in his headspace. And they're only on day one, so they have two more full days to go thanks to some clever re-scheduling efforts on Pepper's part. It's only been a few hours and Tony is more relaxed than he's been in weeks, tears aside. 

Steve bounces the baby again. "I love giving baths. They're just so much fun, right Tony?"

"No," Tony says. It's unquestionably his favorite word when he's in his headspace. Bucky snorts.

"I think someone needs to go down for his nap," he says.

"Nooooo! 'Cano, Dada!" Tony exclaims, wiggling in Steve's arms. He points frantically to the volcano, as though Bucky might have missed it. "'Cano!"

"Sounds to me like someone wants to finish our science experiment before he goes down for his nap," says Steve. "How much longer, Bruce?"

"About fifteen minutes, maybe not even that."

Steve raises his eyebrows at Bucky in silent query. Bucky gives in with a nod, because there's really no point in trying to get Tony down for a nap when he's all fired up about the volcano. And truth be told, Bucky kind of wants to see the volcano explode too. It's not like he got the chance to sit in on sixth grade science experiments while he was being the Winter Soldier.

"Volcano it is!" Steve cheers, bouncing Tony in his arms. "And I think the lava should be red."

"Red!" Tony yells, kicking his legs.

"You people are all so un-creative," Clint grouches, but he's smiling. He tucks Howl under one arm and snags the red coloring, twisting the cap off and holding it out to Tony with a flourish. "Would you like to do the honors, kiddo?"

"I do," Tony says, grabbing the container. Steve steadies his hand, helping the baby to pour some of the coloring into the pitcher of vinegar. The vinegar rapidly darkens into a deep red that looks more like blood than lava, but Bucky's not going to be the one to punch holes in this adventure. Not when Tony looks so excited (and, if Bucky's being honest, everyone else is too. Volcanoes weren't a thing when he and Steve went to school, and apparently Clint, Natasha, Tony and Bruce all missed out on the experience as well for varying reasons. There's a reason they all jumped at the idea when Bruce suggested it).

"Okay. Clint, would you do the honors? Just pour it in there. Try not to spill any," Bruce says, gesturing to the spout of the volcano. Natasha walks over to join them as Clint carefully pours the vinegar in. Steve takes a couple of steps back too, holding Tony tightly.

"Alright, doc, let 'er rip!" Clint declares, shaking the pitcher to get the last few drops of vinegar out.

Bruce shoots him an amused look and dumps baking soda into a paper towel. He ties it up, drops it into the volcano, then steps back. It only takes a minute or two before the combination of baking soda and vinegar bubbles up, frothing over the side of the volcano. Clint whoops and Tony cheers, clapping his hands, as the "lava" runs down the sides of the volcano and over the little lego village that Tony and Bucky had put together. It pools up against the fiberglass base that Steve built and fizzes away.

"You did an excellent job," Natasha says, clapping as well. "Very lifelike."

"I do," Tony says, pointing to the volcano and looking at her for more praise.

Natasha smiles at him. "I know. You worked very hard, Antoshka. I'm proud of you," she says softly, and Tony visibly swells under the praise.

"Again?" he asks, looking hopefully at Bruce. "Again, Uncle Bruce?"

"We could do it with purple lava this time," Clint says, eyes lighting up with inspiration. "Oh man, that would be awesome."

"Well, I don't see why not -" Bruce starts, but he doesn't get any further before the Avengers alarm starts to go off. In the middle of Bruce's lab, it's ear-piercingly loud. Tony flinches and claps his hands over his ears. Natasha calls out an acknowledgement, her voice barely audible over the alarm, and it shuts off abruptly. The lights continue to flash though, which is big Tony's way of making sure that Clint would know about the alarm if he had his hearing aids out.

"I guess we need to head out," Steve says, eyebrows drawing together. They didn't count on this happening. Bucky can practically see their fun, relaxing days jumping out the window. Besides that, now they've got a problem. Tony isn't big enough to report for the call. Someone has to stay with him, and that someone has to be either Bucky or Steve because Tony isn't all the way comfortable with the rest of the team yet.

"Me too," Tony says, struggling a little in Steve's arms. "I can - I can -"

Bucky makes an executive decision and scoops him out of Steve's arms. He has a little more experience in holding squirming babies that don't want to be held and pins Tony easily with an arm around Tony's waist. "You go. I'll stay here with the baby," he says. "Thor and Sam will probably meet you wherever the trouble is. You don't need us tagging along."

Steve looks a little torn for all ten seconds before his expression smoothes out, determination kicking in. "Avengers assemble!" he says, pausing just long enough to chuck Tony under the chin before he leads the rush for the elevator.

"Me too!" Tony says again, struggling harder. "Let go!"

"Tony, hey. Stop that."

"No! Let go!"

"That's enough!" Bucky says, maybe a little too sharply, because Tony's face crumbles. Bucky bites back a sigh and sits down on the couch, holding Tony on his lap. He rocks Tony back and forth for a couple of minutes until Tony's hitched breaths smoothen out and he starts to struggle again.

Then he says, "Tony, you know you're in no condition to pilot the armor."

"Yes I am."

"No, you're not. Baby, two minutes ago you were in tears. I just think you're too little right now." He rubs a thumb under Tony's eyes, wiping away the remains of said tears. Not only that, Tony's been functioning on way too little sleep and part of the reason they've planned these three days is so that he can have the chance to sleep. It also didn't escape Bucky's notice that Tony called him 'Dada' twice, which is a definite hint that Tony's feeling even more little than normal. Mentioning either of those two things will just result in a tantrum, though.

So Bucky settles for saying, "What would you do if Daddy let you go and you were in the armor and you slipped back into your headspace?"

"I wouldn't," Tony says, though unconvincingly. "I help."

"You are a big help, but not today. Today you stay with Daddy."

"I help," Tony whispers, eyes welling up with tears. He starts to quietly sob. Bucky shushes him and gets up once he's sure the rest of the team has departed. He and Tony never discussed what would happen if an alarm went off while they were age playing. He's pretty sure Tony would've made it a rule that he could go anyway, so maybe it's best they didn't. A baby in the armor would be an unmitigated disaster.

He takes Tony up to the communal floor and changes the baby's diaper, then prepares a bottle for him. They settle down on the television together and JARVIS obligingly turns the station to the news. At a glance, it looks like the Avengers are battling Loki. Again. Suddenly, Bucky doesn't feel so bad about staying behind with Tony. Thor might love his brother, but the general consensus amongst everyone else is that Loki's a gigantic pain in the butt.

"Papa!" Tony says, pointing to the screen. Bucky looks just in time to see Captain America fling his shield at Loki's smug face. Unfortunately, Loki disappears before the shield hits.

"Yeah, baby boy. That's your papa," Bucky says, pulling Tony in closer. He pushes the nipple of the bottle in Tony's mouth, relieved that watching the battle seems to have taken Tony's mind off the fact that neither one of them is there. And if they both spend a few minutes giggling after the whole team gets splashed with blue liquid that dyes them all bright pink from head to toe, well. That will just have to remain his and Tony's little secret.

**Author's Note:**

> Find me on [tumblr](http://tsuki-chibi.tumblr.com/).


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